Book shelf display device



FIG. 1 is a rear perspective view of a book shelf display device in an open, shelf-engaged position showing my new design;

FIG. 2 is a front perspective view thereof;

FIG. 3 is a left side elevational view thereof; and,

FIG. 4 is a rear perspective view thereof in a closed, non-engaged position. 

The ornamental design for a book shelf display device, as shown and described. 